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Diffstat (limited to 'man3/fseek.3')
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diff --git a/man3/fseek.3 b/man3/fseek.3 new file mode 100644 index 0000000..4b7a9af --- /dev/null +++ b/man3/fseek.3 @@ -0,0 +1,178 @@ +'\" t +.\" Copyright (c) 1990, 1991 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" Chris Torek and the American National Standards Committee X3, +.\" on Information Processing Systems. +.\" +.\" SPDX-License-Identifier: BSD-4-Clause-UC +.\" +.\" @(#)fseek.3 6.11 (Berkeley) 6/29/91 +.\" +.\" Converted for Linux, Mon Nov 29 15:22:01 1993, faith@cs.unc.edu +.\" +.TH fseek 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +fgetpos, fseek, fsetpos, ftell, rewind \- reposition a stream +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <stdio.h> +.PP +.BI "int fseek(FILE *" stream ", long " offset ", int " whence ); +.BI "long ftell(FILE *" stream ); +.PP +.BI "void rewind(FILE *" stream ); +.PP +.BI "int fgetpos(FILE *restrict " stream ", fpos_t *restrict " pos ); +.BI "int fsetpos(FILE *" stream ", const fpos_t *" pos ); +.fi +.SH DESCRIPTION +The +.BR fseek () +function sets the file position indicator for the stream pointed to by +.IR stream . +The new position, measured in bytes, is obtained by adding +.I offset +bytes to the position specified by +.IR whence . +If +.I whence +is set to +.BR SEEK_SET , +.BR SEEK_CUR , +or +.BR SEEK_END , +the offset is relative to the start of the file, the current position +indicator, or end-of-file, respectively. +A successful call to the +.BR fseek () +function clears the end-of-file indicator for the stream and undoes +any effects of the +.BR ungetc (3) +function on the same stream. +.PP +The +.BR ftell () +function obtains the current value of the file position indicator for the +stream pointed to by +.IR stream . +.PP +The +.BR rewind () +function sets the file position indicator for the stream pointed to by +.I stream +to the beginning of the file. +It is equivalent to: +.PP +.RS +(void) fseek(stream, 0L, SEEK_SET) +.RE +.PP +except that the error indicator for the stream is also cleared (see +.BR clearerr (3)). +.PP +The +.BR fgetpos () +and +.BR fsetpos () +functions are alternate interfaces equivalent to +.BR ftell () +and +.BR fseek () +(with +.I whence +set to +.BR SEEK_SET ), +setting and storing the current value of the file offset into or from the +object referenced by +.IR pos . +On some non-UNIX systems, an +.I fpos_t +object may be a complex object and these routines may be the only way to +portably reposition a text stream. +.PP +If the stream refers to a regular file +and the resulting stream offset is beyond the size of the file, +subsequent writes will extend the file with a hole, up to the offset, +before committing any data. +See +.BR lseek (2) +for details on file seeking semantics. +.SH RETURN VALUE +The +.BR rewind () +function returns no value. +Upon successful completion, +.BR fgetpos (), +.BR fseek (), +.BR fsetpos () +return 0, +and +.BR ftell () +returns the current offset. +Otherwise, \-1 is returned and +.I errno +is set to indicate the error. +.SH ERRORS +.TP +.B EINVAL +The +.I whence +argument to +.BR fseek () +was not +.BR SEEK_SET , +.BR SEEK_END , +or +.BR SEEK_CUR . +Or: the resulting file offset would be negative. +.TP +.B ESPIPE +The file descriptor underlying +.I stream +is not seekable (e.g., it refers to a pipe, FIFO, or socket). +.PP +The functions +.BR fgetpos (), +.BR fseek (), +.BR fsetpos (), +and +.BR ftell () +may also fail and set +.I errno +for any of the errors specified for the routines +.BR fflush (3), +.BR fstat (2), +.BR lseek (2), +and +.BR malloc (3). +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR fseek (), +.BR ftell (), +.BR rewind (), +.BR fgetpos (), +.BR fsetpos () +T} Thread safety MT-Safe +.TE +.sp 1 +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +POSIX.1-2001, C89. +.SH SEE ALSO +.BR lseek (2), +.BR fseeko (3) |